The present invention is directed to an improved strapping machine. More particularly, the present invention is directed to a strapping machine having a work surface having a readily adjustable height.
Strapping machines are in widespread use for securing straps around loads. One type of known strapper includes a strapping head and drive mechanism mounted within a frame. A chute is mounted to the frame, through which the strapping material is fed.
In a typical stationary strapper, the chute is mounted at about a work surface, and the strapping head is mounted to a horizontal portion of the chute, below the work surface. The drive mechanism is also mounted below the work surface, near to the strapping head. The drive mechanism “pulls” or feeds strap material from a source, such as dispenser into the machine. The drive mechanism urges or feeds the strap through the strapping head, into and around the chute, until the strap material returns to the strapping head. The drive mechanism also retracts the strap material to tension the strap around the load.
During the retraction or tensioning portion of the strapping cycle, the strap material must be released from the chute. A typical chute includes inner and outer walls that define a pathway around which the strap is fed. The inner wall (that wall closest to the load), is generally movable so that as the strap is “pulled”, the inner wall moves out of the way (from between the strap and the load), and the strap thus tensions around the load. In some configurations, the inner and outer walls are formed from a plurality of wall sections.
Known chute systems use a plurality of pins, generally located at about the corners of the chute, along with springs and torsion bars to locate and move the wall out of the strap path. While these known systems function well for their intended purposes, it is necessary to assure precise alignment of the pins, over the springs, and generally through openings in the walls or flanges that are formed as part of the walls. In addition, the torsion bars must all be configured so that the walls move in a predetermined sequence, a precise distance, to release the strap.
It has also been found that it is often necessary to access the strapping head (and more specifically the weld head) by removing portions of the work surface. This may be necessary to dislodge misfed strap, to clear the strapping head or weld head, or for general maintenance or repair of the machine. Quite often, it is necessary to access the strap path (by moving the strap chute) at the weld head.
In known strapping machines, to access the strap path it was necessary to move the strap chute by some manual means. For example, known machines include doors or panels that require removal to access these areas of the machine. Others include sprung or biased doors that are biased closed and thus must be held open to access these machine areas.
The strapping or welding head provides a number of functions. First, the strapping head includes a gripper for gripping the strap during the course of a strapping operation. The strapping head also includes a cutter to cut the strap from a strap source or supply. Last, the strapping head includes a sealer to seal a course of strapping material onto another course of material. This seal is commonly referred to as a weld and is effected by heating the overlying courses of the strap. One known heating method is the use of an electrically heated element, referred to as a weld blade or hot blade that is applied to facing sides of overlying courses of strap material. During machine operations, it has been observed that the weld blade can require cleaning fairly often (cleaning is typically carried out by lightly rubbing with an abrasive such as emery cloth).
In known strapping machines, the weld blade is fixed to the strapping head as by fastening to a support. In order to inspect or maintain the weld blade, a multitude of fasteners, such as screws and bolts must be removed from the weld head and support and the blade removed from the head. This can be quite time consuming particularly if, as often happens, the weld blade requires frequent cleaning.
Many such machines are employed in processes that maximize the use of fully automated operation. To this end, machines are configured for automated in-feed and out-feed, such that a load (to be strapped) is automatically fed into the machine by an in-feed conveyor, the strapping process is carried out, and the strapped load is automatically fed out of the machine by an out-feed conveyor. The in-feed and out-feed conveyors are fitted onto the machine at the work surface at either side of the strap chute. Often, the conveyors form a part of the work surface. In this manner, the in-feed conveyor receives the load and moves it into the chute area, the load is strapped and the out-feed conveyor moves the load out of the chute area.
The conveyors can require maintenance on a more frequent basis than the strapper. In addition, in that the conveyor is a load-bearing surface, it may be subjected to additional stresses beyond those to which the machine, generally is subjected.
In addition, as with many process equipment items, strappers are typically manufactured having a predetermined height above the floor at which the work surface is set. However, in that the strapper may be incorporated into other processes or may be used in an area where the strapper work surface height is critical, it may be necessary to vary the height of the strapper. Known machines have no “easy” way to make such height adjustments.
Accordingly there is a need for an improved strapping machine that promotes ready operation and maintenance. Desirably, such a strapping machine includes provisions for a readily adjustable work surface or table height.